The fate of choline in the circulating plasma of the rat

Summary Labelled free choline injected into the peritoneum failed to enter the brain but preferentially entered the liver. Subsequently labelled phospholipid was found in the plasma with a concurrent increase in the brain. This labelled plasma injected by cardiac puncture caused a rapid incorporation of the choline labelled phospholipid into the brain.     

Effect of piperazine on the level of phospholipids and on the activities of certain enzymes of phospholipid metabolism in human Ascaris lumbricoides.

The phospholipid level in the human parasitic nematode Ascaris lumbricoides is decreased by piperazine, by partially stimulating catabolic enzymes such as phospholipase C and partially inhibiting anabolic enzymes such as choline kinase.     

Role of phospholipid transfer protein in rabbit lung development

A 36-kDa phospholipid transfer protein (PLT-P_R), which preferentially transfers phosphatidyl choline (PC) compared to phosphatidyl inositol (PI), was purified 827-fold from rabbit lung homogenate. Incorporation of cholesterol in unilamellar vesicles reduced the PC transfer activity of PLTP_R. Dipalmitoyl phosphatidyl choline uptake by alveolar type II cells was increased in the presence of the protein, and further enhanced in the presence of surfactant liposomes. However, a decrease in uptake was noted with cholesterol in host membranes. Incorporation of PI into host membranes had a low stimulatory effect on the process. All these effects were more pronounced in adult type II cells compared to premature, term and 3-day-old pups. Received 12 September 2001; accepted 11 October 2001     

Effect of piperazine on the level of phospholipids and on the activities of certain enzymes of phospholipid metabolism in humanAscaris lumbricoides

Summary The phospholipid level in the human parasitic nematodeAscaris lumbricoides is decreased by piperazine, by partially stimulating catabolic enzymes such as phospholipase C and partially inhibiting anabolic enzymes such as choline kinase.Acknowledgment. We thank ProfessorP. A. Kurup of this Department for keen interest and helpful advice.     

Intact teratogenic immunoglobulins may reach the rat embryo

It is known that heterologous antiserum against rat kidney homogenate may induce congenital malformations when injected into pregnant rats during the period of organogenesis. Teratogenic rabbit antibodies against a purified rat renal tubular glycoprotein were isolated, labelled with 125I and injected into pregnant rats on the 10th day of gestation. Extracts of visceral yolk-sacs (VYS) and embryos were obtained 16 h later and chromatographed separately on a Sephacryl S-300 gel filtration column. The resultant chromatograms showed several radioactive peaks, one of which coincided with the eluate of intact rabbit immunoglobulins G (IgG). We interpret the result as an indication that some undigested intact teratogenic IgG were present in VYS and the embryo.     

Binucleated neurons in the central nervous system of the laboratory animals

Summary Binucleated neurons were studied in the central nervous system of the rat and the rabbit. They were present in the young as well as the adult animals. The animals injected with thymidine-H³ during their embryonic development showed labelled binucleated neurons. It is suggested that the neurons become binucleated during neuroembryogenesis, and differentiate into normal neurons morphologically and physiologically.Supported by NIH Research grant No. NS-08817-05.     

On the phospholipids of adultAncylostoma caninum

Summary The phospholipid composition ofAncylostoma caninum has been examined. Phospholipids amounted to 0.9% of the wet weight of the parasite. Ethanolamine and choline containing lipids comprised about 76% of the total phospholipids. Lysolecithin, sphingomyelin, phosphatidyl inositol and phosphatidyl serine were present in minor amounts. Cerebrosides and sulfatides were also identified.Acknowledgements. We wish to acknowledge the contributions of Mr Ashok Chopra in the initial part of this work. Thanks are due to Mr Adarsh Kumar for skilled assistance.     

Phospholipid composition of Dipylidium caninum

The phospholipid composition of Dipylidium caninum has been studied. Chloroform-methanol-soluble fraction amounted to 2.4% and phospholipids to 0.5% of the wet weight of the parasite. Phosphatidyl choline and phosphatidyl ethanolamine represented the bulk of the phospholipids, whereas phosphatidyl serine, phosphatidyl inositol, lysolecithin and lysophosphatidyl ethanolamine were present in minor amounts. Sulfatides were also identified in this parasite.     

Age-dependent changes of rat liver plasma membrane composition

The chemical composition of liver plasma membrane was studied in Wistar rats aged between 3 and 24 months. Results obtained indicate a significant age-dependent positive correlation of both the protein: phospholipid and cholesterol: phospholipid ratios, whereas the protein: cholesterol ratio seems to remain unaffected. Phospholipid analysis of liver plasma membrane reveals that only the phosphatidylcholine content has a significant negative correlation with age; all other phospholipid species remain basically unchanged.     

Retention of topical liposomal formulations on the cornea

The ability of liposomes composed of different kinds of phospholipid materials to adhere to the surface of the cornea was studied in the rabbit. The liposomes were labelled with tracer amounts of an I125-labelled phosphatidylethanolamine derivative and were instilled in 10 microliters drops onto the cornea. The retention of radioactivity was monitored. The results show that liposomes containing positively charged phospholipids are better retained than an albumin control. Thus, it may be possible to develop a drug delivery liposome system which would permit long-term sustained release of ophthalmic drugs onto the cornea.     

Phospholipid composition ofDipylidium caninum

Summary The phospholipid composition ofDipylidium caninum has been studied. Chloroform-methanol-soluble fraction amounted to 2.4% and phospholipids to 0.5% of the wet weight of the parasite. Phosphatidyl choline and phosphatidyl ethanolamine represented the bulk of the phospholipids, whereas phosphatidyl serine, phosphatidyl inositol, lysolecithin and lysophosphatidyl ethanolamine were present in minor amounts. Sulfatides were also identified in this parasite.     

A possibility to achieve genetic transformation in the platyfish-swordtail system (Platypoecilus maculatus — Xiphophorus helleri)

Summary In order to determine how informative homologous donor DNA might be made available to propigment cells of the recipientXiphophorus helleri for transformation, labelled heterologous DNA fromE. coli was injected into the neural crest region or the yolk sac of embryos of the recipient. On the basis of the degradation rate of the donor DNA and the incorporation rate of radioactivity into the recipient DNA, it is concluded that injection into the neural crest region may be a suitable method to make available informative homologous donor DNA for transformation.Supported by DFG through SFB No. 103, and by Stiftung Volkswagenwerk.     

The role of apolipoprotein E in lipid metabolism in the central nervous system

The critical roles of apolipoprotein E (apoE) in regulating plasma lipid and lipoprotein levels have been extensively studied for over 2 decades. However, an understanding of the roles of apoE in the central nervous system (CNS) is less certain. This review will summarize the available experimental results on the role of apoE in CNS lipid homeostasis with respect to its modulation of sulfatide trafficking, alteration of CNS cholesterol homeostasis and apoE-induced changes in phospholipid molecular species in specialized subcellular membrane fractions. The results indicate that apoE mediates sulfatide trafficking and metabolism in the CNS. Moreover, although apoE does not affect the cholesterol mass content or the phospholipid mass levels and composition in the CNS as a whole, apoE modulates cholesterol and phospholipid homeostasis in selective subcellular membrane compartments. Through elucidating the roles of apoE in CNS lipid metabolism, new insights into overall functions of apoE in neurobiology can be accrued ultimately, leading to an increased understanding of CNS lipid metabolism and the identification of novel therapeutic targets for CNS diseases.Received 9 January 2004; received after revision 28 February 2004; accepted 10 March 2004     

Opposing temperature responses to intrahypothalamic injections of 5-hydroxytryptamine in the pigeon exposed to cold

Summary 5-Hydroxytryptamine injected into posterior and anterior parts of the pigeon hypothalamus evoked a short lasting hyperthermia or hypothermia, respectively. Variable responses obtained within the same brain region suggest the existence of different 5-HT systems, even in rather limited hypothalamic areas.     

Opposing temperature responses to intrahypothalamic injections of 5-hydroxytryptamine in the pigeon exposed to cold.

5-Hydroxytryptamine injected into posterior and anterior parts of the pigeon hypothalamus evoked a short lasting hyperthermia or hypothermia, respectively. Variable responses obtained within the same brain region suggest the existence of different 5-HT systems, even in rather limited hypothalamic areas.     

Organophosphate-mediated inhibition of choline acetyltransferase activity in rat brain tissue

Administration of the organophosphate compound soman in rats resulted in an inhibition of choline acetyltransferase activity in almost all brain regions examined. Enzyme activity was inhibited by 20-50% in various brain regions 30 min after soman injection (94-120 micrograms/kg). Enzyme activity in two regions decreased with time to a near zero level by 3 h after injection.     

Retention of topical liposomal formulations on the cornea

Summary The ability of liposomes composed of different kinds of phospholipid materials to adhere to the surface of the cornea was studied in the rabbit. The liposomes were labelled with tracer amounts of an I¹²⁵-labelled phosphatidylethanolamine derivative and were instilled in 10 l drops onto the cornea. The retention of radioactivity was monitored. The results show that liposomes containing positively charged phospholipids are better retained than an albumin control. Thus, it may be possible to develop a drug delivery, liposome system which would permit long-term sustained release of ophthalmic drugs onto the cornea.     

Search for sex-dependent and gestation-induced changes in choline and ethanolamine phosphorylating activities.

Choline kinase and ethanolamine kinase of liver, brain and kidney had nearly the same activity in 4-month-old male and virgin female mice. Ethanolamine kinase activity was almost doubled in the liver and brain of mice in advanced pregnancy compared with the virgin, while choline kinase activity was unaltered.     

Effect of fasting on the lipid composition and enzyme activity of rat liver plasma membranes

After 24-h fasting, when the recovery of plasma membrane protein isolated from rat liver was unchanged, the enrichment in 5'-nucleotidase was decreased by 16%. Modifications of the lipid composition were also observed and resulted in a 27% decrease of the cholesterol/phospholipid molar ratio.     

Corticosteroid effects on cholinergic enzymes in ethanol-treated fetal brain cell cultures

In the presence of ethanol, corticosterone and dexamethasone inhibit choline acetyltransferase and acetyl-cholinesterase activities in cultured fetal brain cells of the rat. These results suggest that corticosteroids may have an important influence on the activity of cholinergic enzymes in the fetal brain may antagonize the effects of ethanol in this setting.